The present invention generally relates to integrated lancing test strips, and more specifically, but not exclusively, concerns an integrated lancing test strip with a hydrophilic sheet or flag that is shaped and structured to enhance fluid flow into the test strip as well as maintain the sterility of the test strip.
Body fluid sampling devices have been developed to draw body fluid, such as blood or interstitial fluid, from a person or animal and analyze the drawn fluid for any number of characteristics, such as blood glucose levels for diabetics. Many of these devices have been designed for home based monitoring so that an individual can monitor their condition throughout the day. In a conventional procedure, the medical practitioner or the individual first creates an incision in the skin by lancing the subject's skin with a lancet. To avoid infection of the incision site and/or contamination of the fluid collected, the lancet is sterilized and packaged in a sterile manner prior to use. Typical packaging of the lancet involves covering the tip of the lancet with a protective cap that maintains the sterility of the lancet as wells prevents subjects from accidentally cutting themselves or others with the lancet. Maintaining the sterility of the lancet while at the same time providing for ease in removal of the protective cap can be difficult, especially when the test is self-administered. Usually, the subject is either elderly or otherwise has some infirmity that reduces their hand dexterity, which in turn makes removal of the cap difficult. One solution has been to weaken the connection between the cap and the lancet, but by weakening this connection, the protective caps are more prone to be dislodged during shipping. Complicated systems have been developed to automatically remove the caps, but the caps still tend to be bulky in nature, which makes storage and disposal of the discarded caps problematic in the automatic system. Even with automatic systems, difficulties still exist in ensuring a consistent level of performance when removing the caps. Also, the bulky nature of the caps reduces the packing density of the lancets when attached together in a tape or cassette of lancets.
Usually, after lancing the skin, the individual has to manually position a test strip or a capillary tube in the drop of body fluid, but as mentioned before, this task can be difficult for many individuals, such as the elderly. The ability to draw a sufficient amount of fluid onto the test strip is always a concern, especially with home-based testing systems. When the amount of fluid is insufficient, the individual can become frustrated by having to repeatedly perform the test and waste multiple test strips. For example, if the individual is unable to steadily hold the test strip, the test strip may not collect a sufficient amount of fluid for a reliable test. Also, the user can press the test strip or the sampling device to hard against the skin so that the incision closes, thereby prematurely cutting off the fluid supply. Wicking structures have been developed to help draw fluid onto the test strip or into a capillary tube. However, it has been discovered that these wicking structures have a number of significant drawbacks. For instance, the wicking structures tend to waste fluid by requiring that a considerable amount of the fluid be absorbed by the wicking structure before transporting the fluid to the testing area on the test strip. Also, typical wicking structures are predisposed to smear the droplet of blood or other fluid on the skin, which in turn tends to waste fluid.
After the body fluid sample is collected, the sample may be analyzed for a variety of characteristics through optical and/or electrochemical analysis as well as in other manners. Integrated lancing test strips have been recently developed in which a lancet is attached to a test strip or some other type of testing media, such that the single, integrated unit can both draw and analyze body fluid. Typically, the lancet is made of metal, such as surgical grade stainless steel. In most conventional body fluid sampling devices that use electrochemical test strips, metallic lancets do not significantly affect the readings from electrochemical test strips because the lancet and the electrochemical test strip are separate and spaced relatively far apart. However, with the advent of integrated lancing test strips, it has been discovered that the small spacing between the lancet and electrodes in the test strip can create considerable electrical interference, which can affect the readings generated from the test strip. The electrical interference becomes even more pronounced as the industry tends to shrink the integrated lancing test strips for incorporation into cassettes, cartridges and other types of storage units.
Thus, there remains the need for further improvement in this field.